The Department of Homeland Security's independent watchdog agency has stepped up its oversight of the Secret Service's investigation into the Colombia prostitution scandal.
A DHS official emailed ABC News Monday on behalf of acting Inspector General Charles Edwards to say that late last week the agency "notified the USSS of our intent to conduct a comprehensive review of this matter."
The email followed an ABC News report that revealed that the inspector general's office had taken a back seat in the probe -- leaving the Secret Service's own internal affairs division in control of the investigation into the conduct of its agents during what has been described as an alcohol-fueled night of partying in Colombia.
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Normally, allegations that Homeland Security employees engaged in serious misconduct are a matter for the Inspector General's office to look into. But the agency previously told ABC News that it would instead be monitoring the Secret Service review.
The approach appeared to be the result of a special carve-out for the Secret Service forged a decade ago -- setting it apart from the standard described in a 2009 internal DHS memo, which specifically asserts that the Inspector General is "statutorily responsible for conducting and coordinating all investigations" of wrongdoing by other Homeland Security employees.
Sen. Charles Grassley told ABC News he was not comfortable allowing the Secret Service's own agents to oversee the investigation, especially because it remains unclear whether the raucous behavior in Colombia was a one-time lapse or the sign of a broad systemic problem.
"An investigation by the agency's own Office of Professional Responsibility is necessary, but it doesn't provide transparent, independent oversight without an Inspector General's outside perspective," the Iowa Republican said Wednesday. "There's too much at stake to leave any doubts that an independent investigation wasn't conducted."
In an email to ABC News Monday, Edwards said the agency had enhanced its role in the review. In addition to monitoring the Secret Service effort, the Homeland Security investigators and inspectors would also begin their own independent look back at events.
"Last week, with the initial stages of the USSS [U.S. Secret Service] internal investigation nearing completion, we notified the USSS of our intent to conduct a comprehensive review of this matter," the email said. " As we notified the USSS last week, [the Office of Inspector General's] field work is beginning immediately."